Crane

ABSTRACT

A crane for erection of structural steel, boilers, and the like having a platform, an inner bearing ring for rotatably supporting the platform on a tower or other base, brackets on the platform for supporting a boom foot over the inner bearing ring along the axis of rotation of the platform, a movable boom foot support drawer secured with the platform for supporting the boom foot at a plurality of other positions, a mast mounted on the platform, a boom secured at a foot end to the platform on the boom foot support drawer or the brackets over the inner bearing ring, a gantry mounted on the mast at the center line of rotation of the platform and mast, a gantry block connected with the gantry, a pennant running from the gantry block to the upper end of the boom, a topping line from the platform to the gantry block for raising and lowering the boom, a hoist engine and draw works on the platform connected with load blocks on the boom and with the topping line for raising and lowering the boom and manipulating the load blocks. An outer bearing ring is used around the platform for supporting the platform and boom base when the drawer and boom foot are extended to a position outwardly of the platform. Additional support may be provided by rotatable members running from the top portion of the mast at the gantry to structure spaced from the platform, such as structural steel members of the parent structure being erected with the crane. In one form of the crane, the mast support members are adjustable lay legs. In another form of the crane, the support members are guy wires or cables.

Dec. 2, 1975 United States Patent [1 1 Brewer i 1 CRANE [75] Inventor: Jack J. Brewer, Grapevine, Tex.

[73] Assignee: Sam P. Wallace Company, Inc.,

Dallas TX [22] Filed: Dec. 10, 1973 211 Appl. No.: 423,399

Related 1.1.5. Application Data [63 Continuation-impart of Ser. No. 209,583, Dec. 20,

1971, Pat. No. 3,777,900, and a continuation-in-part of Ser. No. 356,995, May 3, 1973, abandoned.

Primary Examiner--Robert J. Spar Assistant Examiner-Lawrence J. Oresky Attorney, Agent, or Firm-H. Mathews Garland [57] ABSTRACT A crane for erection of structural steel, boilers, and

the like having a platform, an inner bearing ring for rotatably supporting the platform on a tower or other base, brackets on the platform for supporting a boom foot over the inner bearing ring along the axis of rotation of the platform, a movable boom foot support drawer secured with the platform for supporting the boom foot at a plurality of other positions, a mast mounted on the platform, a boom secured at a foot end to the platform on the boom foot support drawer or the brackets over the inner bearing ring, a gantry mounted onthe mast at the center line of rotation of the platform and mast, a gantry block connected with the gantry, a pennant running from the gantry block to the upper end of the boom, a topping line from the platform to the gantry block for raising and lowering the boom, a hoist engine and draw works on the platform connected with load blocks on the boom and with the topping line for raising and lowering the boom and manipulating the load blocks. An outer bearing ring is used around the platform for supporting the platform and boom base when the drawer and boom foot are extended to a position outwardly of the platform. Additional support may be provided by rotatable membersrunning from the top portion of the mast at the gantry to structure spaced from the platform, such as structural steel members of the parent structure being erected with the crane. In one form of the crane, the mast support members are adjustable lay legs. In another form of the crane, the support members are guy wires or cables.

21 Claims, 6 Drawing Figures US. Patent Dec. 2, 1975 -Sheet10f3 v3,923,163

US. Patent Dec. 2, 1975 Sheet 2 of3 3,923,163

Sheet 3 of 3 U8. Patent Dec. 2, 1975 CRANE This application is a continuation-in-part of earlier filed pending applications of Applicant for Letters Patent of the United States, Ser. No. 209,583, entitled BUILDING CRANE filed Dec. 20, 1971, now U.S. Pat. No. 3,777,900 issued Dec. 11, 1975, and Ser. No. 356,995 entitled STIFF-LEG CRANE filed May 3, 1973, now abandoned.

This invention relates to cranes and more particularly relates to building cranes.

Currently available cranes, particularly for the erection of steel structures, are of limited flexibility. Those cranes of the stiff-leg type do not provide legs which are readily adjustable in position and length. Also, such cranes have a fixed location for the boom, thereby precluding the flexibility available in the present crane wherein the boom foot may be positioned at a number of selected locations on the crane base platform. With the use of only a centrally located boom foot of the type in the usual guy or stiff-leg derrick, the lifting capacity is somewhat limited. Additionally, most presently available guy derricks or stiff-leg derricks are not usable only with the legs or guy wires connected to some outlying member around the crane.

It is a principal object of the invention to provide a new and improved building crane.

It is another object of the invention to provide a new and improved crane which may be used in a number of different forms.

It is another object of the invention to provide a crane which may be used with or without either lay legs or guy wires.

It is another object of the invention to provide a new and improved crane which has a movable boom foot.

It is another object of the invention to provide a crane which uses a single inner ring bearing support on both an inner ring and an outer bearing ring around the crane platform to rotatably support the crane base platform.

In accordance with the invention there is provided a crane having a base platform, an inner bearing ring for rotatably supporting the base platform, a pair of brackets for supporting a boom foot over the inner base ring, a movable boom foot support drawer for securing the boom foot at a plurality of locations along the platform and extended from an end of the platform, a mast mounted on the platform on the axis of rotation of the platform, a gantry on the mast on the axis of rotation of the mast and platform, a gantry block and boom topping pennant connected with the gantry, a hoist engine and draw works on the platform, an operator cab on the platform, a boom secured at a foot end to the brackets over the bearing ring or the boom foot support drawer, load blocks on the boom, a topping line and load lines connected with the draw works extending to the gantry block and to the load blocks on the boom, and support members connected with the mast and adapted to be connected with support members such as parent structure being erected by the crane and spaced from the platform. The crane is usable with or without the support members. One form of the crane uses movable lay legs while another form uses guy wires. An outer bearing ring may be used when the boom foot is extended outwardly from the platform on the boom support drawer.

The foregoing objects and advantages together with the details of preferred forms of cranes incorporating the features of the invention will be better understood by reading the following detailed description taken in conjunction with the accompanying drawings wherein:

FIG. 1 is a side view in elevation, partly broken away, of a crane constructed in accordance with the invention, showing supporting parent structure in broken lines;

FIG. 2 is an enlarged fragmentary side view in elevation of the base end of the mast, the platform of the crane, and the outer bearing ring;

FIG. 3 is a fragmentary view in section and elevation taken along the line 3-3 of FIG. 1;

FIG. 4 is atop plan view of the crane platform and related structure taken along the line 44 of FIG. 2;

FIG. 5 is a fragmentary perspective view showing the top of the mast, the gantry, and lay legs of the crane of FIG. 1; and

FIG. 6 is a fragmentary perspective view of the top of the mast and gantry of an alternate guy derrick form of the crane of FIG. 1.

Referring to FIG. 1, a crane 10 embodying the features of the invention includes a mast 11 mounted on a platform 12 supported on an inner ring bearing 13 mounted on a framework 14 which is secured to a parent steel structure 15. A boom 20 having a boom foot 21 is selectively secured at any one of a plurality of locations on the platform for varying the load conditions on the crane. A hoisting engine and draw works 22 and an operators cab 23 are mounted on the platform. Load and whip lines 24 and 25, respectively, run from the hoist to blocks 30 and 31 supported from the upper free end 32 of the boom. A gantry 33 is mounted on the top of the mast connected by a gantry block 34 with a topping rig 35 extending to the boom end 32 for supporting and raising and lowering the boom between desired angular positions. The particular form of the crane shown in FIG. 1 includes a pair of identical lay legs 40 and 40 which are rotatably secured along a top portion of the mast 11 for added support for the mast from the parent structure being erected with the crane. In the arrangement illustrated, the lay leg 40 is secured at an outward lower end by clamps 41 with an I beam 42 of the parent structure 15 and the leg 40' is similarly secured as in FIG. 5 at an angle to the leg 40 to provide support to the mast from a substantial distance horizontally from the platform 12 to increase the capacity of the crane and reduce the overturning moment. Thus, the crane 10 has the capability of relocation of the boom foot and the use of the adjustable lay legs 40 and 40 to provide maximum load handling flexibility.

The load handling characteristics of the crane are varied by selective location of the boom foot 21 ranging from along the axis of rotation of the platform over the bearing ring 13 or to substantially outwardly from the end 12a of the platform. Details of the structure for securing the boom foot at these locations are illustrated in FIGS. 2, 3 and 4. The mast 11 is formed by four legs 50 secured at lower ends to identical brackets 51 on the four corners of the rectangular box-shaped base platform 12. The vertical axis of the mast is coincident with the axis of rotation of the platform. The platform has a top deck or floor 52 on which are secured a pair of spaced upwardly extending brackets 53. The brackets 53 are mounted along opposite sides of the platform over the bearing ring 13 along a diameter of the ring intersecting the axis of rotation of the platform and mast and perpendicular to the sides of the platform. When location of the boom foot at the center of rotation of the mast and platform is desired. the boom foot is mounted on a horizontal shaft or axle, not shown, extending through the holes in the two spaced brackets 53.

When the mounting of the boom foot outwardly from the inner bearing ring 13 at the axis of rotation is desired, the foot is secured on an adjustable support drawer 54 which slides in a box-like pocket 55 formed on the platform floor 52 as best seen in FIG. 3. The pocket 55 is in a box-like structure having a bottom, top and sides and open at the platform end 12a. The top of the pocket member 55 provides a floor surface for mounting the hoist engine and draw works and other platform accessories. A portion of the top of the pocket is open as seen in FIG. 4 to allow maximum drawer movement for boom positions ranging from the extended location of FIG. 4 inwardly to a location over the ring 13 nearest the platform end 12a. The top of the drawer 54 has a pair of spaced brackets 60 through which a shaft 61 extends supporting the boom foot 21. The drawer 54 is held at any one of several desired positions in the pocket by a rod 62 which extends through holes 63 in the side walls of the drawer and corresponding holes in the side walls forming the pocket 55. To add further support to the boom foot when mounted on the pocket with the pocket extended as shown in FIGS. 2 and 4, an outer bearing ring formed by a circular I beam 64 is mounted on the parent structure substantially outwardly from the inner ring 13. A pair of rollers 65 are secured within the bottom of the drawer 54 located so that the lower periphery or tread of each of the rollers extends downwardly below the drawer as shown in FIG. 2 to ride on the top flange of the ring 64. As the platform and mast rotate, the rollers 65 travel along the top flange of the ring 64 so that the boom foot transfers any load on the boom directly to the ring thereby minimizing the overturning moment applied to the top of the mast through the bottom topping rig. The top of the pocket structure is cut out from the front edge of the pocket at the platform end 12a inwardly toward the hoist defining a rectangular top opening 56 as shown in FIG. 4 so that side retainer flanges 57 are formed along each side of the opening 56 at the top of the pocket structure for holding the drawer 54 while allowing it to move inwardly into the pocket structure to the position shown in FIG. 1 at which the boom foot rests over the inner bearing ring 13. The boom foot may be moved to any desired location from the extended position represented in FIG. 2 at which it has the additional support of the outer ring 64 inwardly to the position shown in FIG. 1 at which the boom foot rests over the inner bearing ring 13. Additionally, the boom foot may be disconnected from the support drawer and reconnected with the brackets 53 at which the boom foot rests over the bearing ring 13 aligned with the axis of rotation of the mast and mast platform.

If the load conditions permit. the crane may be used without the additional support as provided by such features as the lay legs 40 and 40 with all of forces being transferred to the parent supporting structure through either the inner bearing ring 13 or both the inner bearing ring and the outer ring 64. Under such circumstances the boom foot is adjusted to a base location on either the brackets 53 or the support drawer 54 as required by the operating and load conditions.

Still further load increases as much as about 52% may be handled by the crane by using the lay legs 40 or guy wires as represented in FIG. 6. Referring to FIGS. 1 and 5, the identical lay legs 40 and 40 each include a pair of telescoping first and second sections and 71. The section 71 telescopes into the section 70 and is adjustably connected for varying the length of each of the lay legs by a bolt 72 which passes through a selected pair of holes 73 in the section 70 and a hole in the upper end portion of section 71. Each of the legs is provided with a foot 74 having side flanges 75 which are secured by the brackets 41 to a beam of the parent structure 15 such as designated by the reference numeral 42 in FIG. 1. The upper end of the section 70 of each of the lay legs is pivotally connected along the top portion of the mast 11. The section 70 of the lay leg 40 is secured to a bracket connected with a pair of spaced bearing rings 81 and 82 which revolve on a vertical, cylindrical shaft 83 forming the top portion of the mast 11. The section 70 of the lay leg 40' is similarly connected with a bracket 84 secured to a central hearing sleeve 85 which also fits around the shaft 83 between the bearing rings 81 and 82. By intermeshing the bearing rings for the upper ends of each of the lay legs, the lay legs connect with the mast at the same elevation. The lay legs may be maneuvered to any desired positions within a circle about the mast as suggested in FIG. 5. Preferably, the lay legs are secured degrees apart as shown in FIG. 5 in a quadrant of the circle about the mast generally opposite the area in which the boom is operating. With the lay legs connected to the parent structure at the locations shown in FIG. 5, the boom is operable about the mast around approximately 270 degrees. When work is completed within the 270 degree area shown in FIG. 5, the lay legs are readily disconnected, rotated about the mast, and resecured to other parts of the parent structure to allow the boom to work within the quadrant which was blocked off in the illustration of FIG. 5. Further details relating to the manipulation of the lay legs are discussed in the copending applications of ApplicantSer. No. 356,995, supra.

A still further arrangement for supporting the mast 11 of the crane from the parent structure being erected is with the use of guy cables or lines as illustrated in FIG. 6. Three guy cables are preferred, designated by the reference numerals 90, 91 and 92, each of which is secured to the vertical shaft 85 of the mast so that the cables are readily rotated about the mast for connection at various angles to the parent structure. The cable 90 is secured with brackets 93 connected with spaced lower and upper bearing rings 94 and 95 which rotate on the shaft 85. The cable 91 is connected with brackets secured with an upper bearing ring 101 and a lower bearing ring 102 which also rotate on the shaft 85. Similarly, the guy cable 92 is secured to brackets 103 which are connected with a central bearing sleeve 104 rotating on the shaft 85. The lower outer ends of the guy cables 90, 91 and 92, not shown, are each secured to various members of the parent structure by suitable standard brackets, hooks, or clamps for providing additional support to the mast. The technique of handling the guy cables and the arrangement of the cables with respect to the angles at which they are connected to the parent structure conform to standard procedure used with other'types of guy derricks. The guy 'cables provide support similar to that supplied by the lay legs from locations on the parent structure spaced from'the mast to permit substantially increased loads to be supported and manipulated from the boom.

The base platform mayinclude drive means associjustability of the boom foot and thecapability of the connecting additional support means to the top of the mast provide-different loading ranges in which the crane may be used depending upon the arrangement of the supporting structiire andt the position of the boom foot. As previously discussed, theboom foot may be secured at the center of rotation of the :mast to the side brackets 53 or it may-b'e secured with the brackets 60 on the drawer 54 and moved-'onthedrawer from an in.-

.ward position over the inner bearing ring 13 to an outward position as represented in FIGS. 2 and 4. The outer support ring 64 ispreferably used when the boom foot is supported outwardly from the platform in accordance with FIGS. 2 and 4. In addition to the various locations for the boom foot and the selected use of either the inner bearing ring 13 only or both the inner bearing ring and the outer ring 64, the crane may also be fitted with either the lay legs 40 and 40 or the guy cables 90, 91 and 92. Such a crane provides a simple tool for the erection of structural steel and boilers. It is basically a lightweight apparatus which may be supported from the structural steel being erected or may be mounted on a conventional tower within or to the side of the structure being assembled. The lifting capacity of the crane is initially increased about 35 over conventional cranes having the boom foot at a central position by movement of the boom foot to the location of the outer ring 64. The lifting capacity of the crane is still further increased by the use of the lay legs or guy cables. The supporting of the operator cab and the hoist unit on the crane platform eliminates lines to the ground and places the operator at the same level as the crew.

What is claimed is:

1. A crane comprising: a base platform; rotatable support means for said platform; a mast mounted on said platform having a vertical axis coincident with the axis of rotation of said platform on said rotatable support means; a boom having a boom foot; pivot means for pivotally securing said boom foot to said platform in load bearing operating relationship at a selected one of a plurality of locations along said platform; bracing means for the upper end portion of said mast securable between said mast and support structure independent of said base platform and spaced horizontally from said base platform; horizontally reciporable means for securing said pivot means on said platform for movement of said boom foot to any one of several locations ranging from alignment with said axis of rotation of said mast to outwardly of one end of said base platform.

2. A crane in accordance with claim 1 wherein said bracing means comprises at least two lay legs each rotatably secured at one end with said top portion of said mast and securable at the opposite end with said support structure spaced from said base platform.

- 3'. A'crane in accordance with claim 2 wherein said lay'legs are adjustablein length and angle of inclination with said mast.

' 4. A crane in accordance with claim 3 wherein said rotatable support means for said platform comprises an inner bearingring under'said' platform.

5. Acrane in accordance with claim 4, including an outer bearing-'ring su'pported independently ofand around said platform and means on said platform for supporting said boom foot and extendable" to engage said outer bearin'g'ri'ng fo'r supporting said boom foot outwardly of on'eend of said'platform. i

6. A crane in accordance with claim 1 wherein said bracing means comprisesa pluralityof guy cables connected with said upper end portion of said mast.

7. A crane in accordance with claim "6 wherein said rotatibl support means for said platform comprises an inner bearing ring. 1 I

8. crane in accordance'with claim 7 including an outer bearing ring supported independently of said platform around said platformahd means on said platfoi'm for supporting saidboom foot and extendable for engaging said outerbearing ring to support said boom foot outwardly of an end-of said platform; 9. A- crane in acc ordance-withclaim 1 including bracing means for securing a top portion of said mast with support structure independent of and horizontally spaced from said base platform.

10. A crane in accordance with claim 9 wherein said bracing means comprises at least two lay legs each rotatably secured at one end with said top portion of said mast and connectible at the opposite end with said support structure.

11. A crane in accordance with claim 10 wherein said lay legs are adjustable in length and angle of inclination with said mast.

12. A crane in accordance with claim 9 wherein said bracing means comprises a plurality of guy cables each connected at one end with said upper portion of said mast and connectible at the opposite end with said support structure.

13. A crane in accordance with claim 1 wherein said rotatable support means for said platform comprises an inner bearing ring under said platform.

14. A crane in accordance with claim 13 including an outer bearing ring supported around said platform independently of said platform, and means on said platform extendable to operate on said outer ring to support said boom foot outwardly of said end of said platform to provide additional support to said platform when said crane foot is secured at a location outwardly of the base end of said mast.

15. A crane in accordance with claim 1 wherein said rotatable support means for said platform comprises an inner bearing ring.

16. A crane in accordance with claim 15 including an outer bearing ring supported around and independently of said platform and extendable means on said platform for supporting said boom foot outwardly of one end of said platform and for rotatably supporting an outer portion of said platform from said outer ring when said boom foot is secured at a location outwardly of said end of said platform.

17. A crane comprising: a base platform; an inner bearing ring secured on the bottom of said base platform for rotatably supporting said platform; a vertical mast mounted on said platform having a base end including legs extending to positions on said platform outwardly of said base bearing ring, the vertical axis of said mast being coincident with the axis of rotation of said platform on said base ring; a boom having a boom foot; brackets on said platform over said inner base ring aligned with said axis of rotation of said platform on said base ring and said vertical axis of said mast for securing said boom foot to said platform; pocket and track means formed on said base platform opening at a first end of said platform; a boom foot support drawer slidable in said pocket to support said boom foot at a plurality of locations along said platfonn ranging from a first location over said inner base bearing ring to a location outwardly from said first end of said platform; brackets on said drawer for securing said boom foot of said boom with said drawer; a boom top rigging assembly secured between the upper end of said boom and the upper free end of said mast for selectively adjusting the angular position of said boom relative to said platform; an operator's cab on said platform; hoist means on said platform; load blocks and lines on said boom connected with said hoist means.

18. A crane in accordance with claim 17 including at least two lay legs pivotally and rotatably connected at first ends with an upper end portion of said mast and having means at opposite ends for connection with structure independent of and spaced outwardly from said base platform.

19. A crane in accordance with claim 18 including an outer bearing ring supported independently of said platform and engageable by said boom foot support drawer when said drawer is extended for supporting said drawer and said boom foot at said extended position, said platform and drawer being rotatable on said inner and outer rings.

20. A crane in accordance with claim 17 including guy cables connected with said upper end portion of said mast and connectible with structure independent of said base platform spaced horizontally outwardly from said platfonn for supporting said mast from said structure.

21. A crane in accordance with claim 20 including an outer bearing ring supported independently of said platform and engageable by said drawer supporting said boom foot when said drawer and said boom foot are extended outwardly from said first end of said platform permitting rotation of said platform and said boom foot on said drawer on said inner and outer rings. 

1. A crane comprising: a base platform; rotatable support means for said platform; a mast mounted on said platform having a vertical axis coincident with the axis of rotation of said platform on said rotatable support means; a boom having a boom foot; pivot means for pivotally securing said boom foot to said platform in load bearing operating relationship at a selected one of a plurality of locations along said platform; bracing means for the upper end portion of said mast securable between said mast and support structure independent of said base platform and spaced horizontally from said base platform; horizontally reciporable means for securing said pivot means on said platform for movement of said boom foot to any one of several locations ranging from alignment with said axis of rotation of said mast to outwardly of one end of said base platform.
 2. A crane in accordance with claim 1 wherein said bracing means comprises at least two lay legs each rotatably secured at one end with said top portion of said mast and securable at the opposite end with said support structure spaced from said base platform.
 3. A crane in accordance with claim 2 wherein said lay legs are adjustable in length and angle of inclination with said mast.
 4. A crane in accordance with claim 3 wherein said rotatable support means for said platform comprises an inner bearing ring under said platform.
 5. A crane in accordance with claim 4 including an outer bearing ring supported independently of and around said platform and means On said platform for supporting said boom foot and extendable to engage said outer bearing ring for supporting said boom foot outwardly of one end of said platform.
 6. A crane in accordance with claim 1 wherein said bracing means comprises a plurality of guy cables connected with said upper end portion of said mast.
 7. A crane in accordance with claim 6 wherein said rotatable support means for said platform comprises an inner bearing ring.
 8. A crane in accordance with claim 7 including an outer bearing ring supported independently of said platform around said platform and means on said platform for supporting said boom foot and extendable for engaging said outer bearing ring to support said boom foot outwardly of an end of said platform.
 9. A crane in accordance with claim 1 including bracing means for securing a top portion of said mast with support structure independent of and horizontally spaced from said base platform.
 10. A crane in accordance with claim 9 wherein said bracing means comprises at least two lay legs each rotatably secured at one end with said top portion of said mast and connectible at the opposite end with said support structure.
 11. A crane in accordance with claim 10 wherein said lay legs are adjustable in length and angle of inclination with said mast.
 12. A crane in accordance with claim 9 wherein said bracing means comprises a plurality of guy cables each connected at one end with said upper portion of said mast and connectible at the opposite end with said support structure.
 13. A crane in accordance with claim 1 wherein said rotatable support means for said platform comprises an inner bearing ring under said platform.
 14. A crane in accordance with claim 13 including an outer bearing ring supported around said platform independently of said platform, and means on said platform extendable to operate on said outer ring to support said boom foot outwardly of said end of said platform to provide additional support to said platform when said crane foot is secured at a location outwardly of the base end of said mast.
 15. A crane in accordance with claim 1 wherein said rotatable support means for said platform comprises an inner bearing ring.
 16. A crane in accordance with claim 15 including an outer bearing ring supported around and independently of said platform and extendable means on said platform for supporting said boom foot outwardly of one end of said platform and for rotatably supporting an outer portion of said platform from said outer ring when said boom foot is secured at a location outwardly of said end of said platform.
 17. A crane comprising: a base platform; an inner bearing ring secured on the bottom of said base platform for rotatably supporting said platform; a vertical mast mounted on said platform having a base end including legs extending to positions on said platform outwardly of said base bearing ring, the vertical axis of said mast being coincident with the axis of rotation of said platform on said base ring; a boom having a boom foot; brackets on said platform over said inner base ring aligned with said axis of rotation of said platform on said base ring and said vertical axis of said mast for securing said boom foot to said platform; pocket and track means formed on said base platform opening at a first end of said platform; a boom foot support drawer slidable in said pocket to support said boom foot at a plurality of locations along said platform ranging from a first location over said inner base bearing ring to a location outwardly from said first end of said platform; brackets on said drawer for securing said boom foot of said boom with said drawer; a boom top rigging assembly secured between the upper end of said boom and the upper free end of said mast for selectively adjusting the angular position of said boom relative to said platform; an operator''s cab on said platform; hoist means on said platform; load blocks and lines on said boom connected with said hoist means.
 18. A crane in accordance with claim 17 including at least two lay legs pivotally and rotatably connected at first ends with an upper end portion of said mast and having means at opposite ends for connection with structure independent of and spaced outwardly from said base platform.
 19. A crane in accordance with claim 18 including an outer bearing ring supported independently of said platform and engageable by said boom foot support drawer when said drawer is extended for supporting said drawer and said boom foot at said extended position, said platform and drawer being rotatable on said inner and outer rings.
 20. A crane in accordance with claim 17 including guy cables connected with said upper end portion of said mast and connectible with structure independent of said base platform spaced horizontally outwardly from said platform for supporting said mast from said structure.
 21. A crane in accordance with claim 20 including an outer bearing ring supported independently of said platform and engageable by said drawer supporting said boom foot when said drawer and said boom foot are extended outwardly from said first end of said platform permitting rotation of said platform and said boom foot on said drawer on said inner and outer rings. 